Punching device having adjustable guide retainer

ABSTRACT

A punching device includes a C-frame on which a punch and stripper assembly is upwardly urged by a lifter spring, there being a rotatably adjustable retainer plate having various shoulders positionable in a recess in the stripper sleeve for selecting the pinch point clearance, namely the clearance between the stripping sleeve and the die.

United States Patent 1191 von Langendorff Dec. 16, 1975 1 PUNCI'IING DEVICE HAVING ADJUSTABLE GUIDE RETAINER [75] Inventor: Vitmar G. von Langendorff,

Tonawanda, NY.

[73] Assignee: Houdaille Industries, Inc., Buffalo,

[22] Filed: Feb. 14, 1975 [21] Appl. No.: 550,759

[52] US. Cl. 83/140; 83/546; 83/700 [51] Int. Cl. B26D 7/22; B26D H06 [58] Field of Search 83/140, 138, 397.1, 398,

{56] References Cited UNITED STATES PATENTS 2,708,970 5/1955 Taylor 83/140 Grossman 83/140 Weisbeck 83/140 Primary Examiner-Willie G. Abercrombie Attorney, Agent, or Firm-Hi1l, Gross, Simpson. Van Santen, Steadman, Chiara & Simpson [5 7] ABSTRACT A punching device includes a C-frame on which a punch and stripper assembly is upwardly urged by a lifter spring, there being a rotatably adjustable retainer plate having various shoulders positionable in a recess in the stripper sleeve for selecting the pinch point clearance, namely the clearance between the stripping sleeve and the die.

10 Claims, 4 Drawing Figures US. Patent Dec. 16, 1975 3,926,082

ii III PUNCHING DEVICE HAVING ADJUSTABLE GUIDE RETAINER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a punching device of the sub-press type for use in a punch press, press brake or the like.

2. Prior Art It is desirable and necessary to have an air gap between a retracted punch-guide-and-stripper assembly and die which is larger than the maximum thickness of the material that the punching device can perforate. Where the device is one that is considered to be of the heavy duty type, there is thus provided a substantial gap to accommodate such a workpiece. However, such punching device is also capable of handling thinner workpieces. When a relatively thin workpiece is placed on such a die for punching, there is a considerable air gap between the top surface of the workpiece and both the punch tip and the stripper sleeve, the gap under the punch tip and the stripper sleeve being considered ex cessive for operator safety by OSHA, OSHA referring to such gap as the point of operation". Thus, when punching thinner workpieces, it has been necessary to provide a suitable guard for operator safety or to use punching equipment having less capacity so that a smaller gap can be initially provided. Neither of these alternatives is desirable for several reasons.

SUMMARY OF THE INVENTION In this invention, OSHA requirements are met by providing a retainer plate that holds the stripper sleeve in a selected one of a plurality of vertical spaced positions, when retracted, so that when working with thinner material in a heavy duty press, the clearance at the pinch point can be selectably reduced to provide operator safety in accordance with OSHA requirements. With this construction, the sleeve not only guides the punch and serves a stripping function, but also serves a safety guarding function around the punch tip.

Accordingly, it is an object of the present invention to provide a punching device wherein the clearance between the stripper sleeve and the die, when one is retracted from the other, is just barely larger than the workpiece thickness, whereby the need for a separate guard around the sleeve is avoided.

Another object of the present invention is to provide a construction for a punching device wherein the clearance above a workpiece in such punching device at the pinch point can be adjusted in increments of one-eighth inch.

Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheet of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.

ON THE DRAWING FIG. 1 is a fragmentary side view of a punching device in accordance with the present invention;

FIG. 2 is a fragmentary cross-sectional view taken along line IIII of FIG. 1 with the punch removed, a retainer plate being at a first position corresponding to that of FIG. 1;

2 FIGS. 3 and 4 correspond to FIG. 1 but with the retainer plate placed at other positions.

AS SHOWN ON THE DRAWINGS The principles of the present invention are particularly useful when embodied in a punching device of the sub-press type such as shown fragmentarily in FIG. 1 generally indicated by the numeral 10. The punching device includes a frame 11 such as of the C-frame type having a lower arm 12 supporting a die 13, and an upper arm 14 having a vertical bore 15 in registration with the die 13.

In the bore 15, the upper arm 14 supports and guides a punch and stripper assembly which includes a punch guide and stripper sleeve 18, having a recess 16 which faces the bore 15, the lower end of the recess 16 being a shoulder 17 which faces away from the die 13. A punch 19 having a body 20 is slidably guided in a bore 21 of the stripper sleeve 18, and a stripper spring 22 which may be a single spring but which is here shown as being a plurality of Belleville springs arranged in a nonnested manner. The stripping spring 22 acts between the upper surface 23 of the stripper surface sleeve 18 and a lower surface 24 of a punch head 25 to urge the punch 19 in a direction so as to draw the punch body 20 and its cutting tip into the stripper sleeve 18 so that an upper surface 26 of the punch body engages an internal downwardly directed shoulder 27 forming a part of and disposed within the stripper sleeve 18. The punch 19 and stripper sleeve 18 preferably include keying means for angularly orienting the punch 19 with respect to the frame 1 1, such keying means here comprising and elongated slot (not shown) in the stripper sleeve 18 and a key (not shown) secured to the body 20 of the punch 19. Corresponding keying angularly orients the stripper sleeve 18 directly with the frame 11, such keying means here comprising an elongated slot 28 in the stripper sleeve 18 and a key 29 retractably secured to the upper arm 14 of the frame 11.

A lifting spring 30 acts between the upper surface of the upper arm 14 and the lower side of a flange 31 on the stripper sleeve 18 to retract the punch and stripper assembly, namely to retract the stripper sleeve 18 along with the punch 19 and the stripper spring 22 so as to provide maximum clearance between the die 13 and the lower surface of the upper arm 14.

To retain the punch 19 and the stripper sleeve 18 in the upper arm, and more particularly to retain such components at a selected height, there is provided a retainer plate 32 on the upper surface of the upper arm 14 in such position that a circular peripheral portion thereof may overlap the bore 15.

The retainer plate 32 has three circular peripheral portions 33, 34 and 35 which can overhang the bore 15 located in three quadrants while the fourth quadrant includes a peripheral portion 36, the outer edge of which is flat and forms a vertical clearance wall 37 which, when the retainer plate is moved, is substantially tangential to the bore 15 with a slight clearance between it and the sleeve 18 to enable removal of the sleeve. A pair of partial vertical clearance walls 38,39 form part of the peripheral portions 33,35, the three clearance walls jointly being disposed as three sides of a square. The peripheral portion 34 has a vertical extent that is the same as the thickness of the retainer plate 32 while the peripheral portions 33,35 are under cutup to the vertical walls 38,39 to provide a pair of downwardly facing shoulders 40,41. The lower surface of the peripheral portion 34 can also be considered as being a shoulder 42. Each of the three shoulders 40-42 faces downwardly, namely toward the die and are each located at different distances from the die 13. Each of the shoulders 40-42 respectively can engage the sleeve shoulder 17 in response to having been repositioned in registration therewith.

The peripheral portions 33-35 overhang the bore so that in operation, one of those three projects into the sleeve recess 16 and also projects beneath the lower end of the lifting spring 30, each having a circular periphery as best seen in FIG. 2.

The retainer plate 32 has a central opening 43 within which is snugly received a central non-threaded bearing portion 44 of a shoulder screw generally indicated at 45.

The retainer plate 32 is movably secured to the upper side so that various ones of the shoulders 40-42 may be moved into registration with the shoulder 17. Thus the shoulder screw 45 not only secures the retainer plate 32 to the upper side of the upper arm but also provides guidance by which the same may be rotated without loss of or change of radial position. In this embodiment, the upper arm 14 is recessed at 46 to provide peripheral clearance for the retainer plate 32, the recess 46 being of such depth that the upper surface 47 of the retainer plate 32 is coplanar with the upper surface of the arm 14.

At a point eccentric to the axis of the shoulder screw 45, detent means generally indicated at 48 are provided for acting between the upper arm 14 and the retainer plate 32. In this embodiment, the detent means includes a spring biased ball 49 which is received in one of four ball-receptive recesses 50-53, the recesses 50, 52, 53 being openings that extend through the retainer plate 32. The recesses 50-53 are located a uniform distance from the axis of the shoulder screw 45, and the detent means 48 functions to accurately locate each of the four peripheral portions 33-36 in a predetermined angular position.

In order to provide the greatest possible clearance for the workpiece, the retainer plate is positioned as shown in FIGS. 1 and 2. To reduce the clearance, such as by one-eighth inch, the retainer plate 32 is rotated to the position shown in FIG. 3. A pointed instrument may be inserted in the recess 53 to facilitate such rotation, the detent means 48 having assisted in the final accurate angular location of the retainer plate 32. In order to further reduce the clearance by one-eighth inch, the retainer plate 32 is rotated so that the portion 34 projects into the recess 16 for engaging the sleeve shoulder 17.

When a punching force is applied to the head 25, the relatively weak lifter spring 30 first yields, thus completely closing the gap between the lower edge of the stripper sleeve 18 and the workpiece, this area having been referred to herein as the pinch point. As reaction from the non-apertured portion of the die 13 prevents further downward movement of the stripper sleeve 18, further ram movement advances the punch with its tip in an opposition to the stripping spring 22 and of course the reaction to the punching operation itself. When punching thin workpieces, the retainer plate 32 is set as shown in FIG. 4 from which it is evident that from a safety standpoint, it would be difficult to have the operators fingers accidentally get under the punch and sleeve.

Although various minor modifications may be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon, all such embodiments as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

1. A punching device comprising:

a. a frame having a lower arm on which a die is supported, and an upper arm having a vertical bore aligned therewith;

b. a punch-guide and stripper sleeve slidably disposed in the bore in said upper arm, there being a recess facing said bore and defining a shoulder facing away from said die;

c. a punch having a body slidably disposed in said sleeve;

(1. a stripping spring acting between said sleeve and said punch to urge the lower end of said punch into said sleeve;

e. a lifting spring acting between said sleeve and said upper arm and urging said sleeve away from said die; and

f. a retainer plate movably secured to the upper side of said upper arm, said plate having a plurality of peripheral portions for overhanging said bore and projecting into said recess of said sleeve, said portions each having a shoulder (l) facing toward said die, (2) being located at differing distances from said die, and (3) being respectively engageable with said shoulder on said sleeve in response to horizontal repositioning of said plate.

2. A punching device according to claim 1 in which each of said peripheral portions project beneath said lifting spring for engaging said shoulder on said strip per sleeve.

3. A punching device according to claim 1 in which the upper surface of said retainer plate is coplanar with the upper surface of said upper arm.

4. A punching device according to claim 1 including a shoulder screw securing said plate to said upper arm,

said shoulder screw having a central non-threaded bearing portion having a close fit with said retainer plate to position it accurately.

5. A punching device according to claim 1 in which said plate is circular at each said peripheral portion, said plate having a further peripheral portion movable to a substantially tangential relation to said bore where it has clearance with respect to said stripper sleeve.

6. A punching device according to claim 1 which includes detent means acting between said upper arm and said retainer plate for accurately locating each of said peripheral portions of said retainer plate.

7. A punching device according to claim 6 in which said retainer plate is rotatably mounted for movement about a vertical axis, said detent means including a plurality of detent elements disposed a uniform distance from said axis.

8. A punching device according to claim 7 in which said detent elements are ball-receptive recesses on said retainer plate.

9. A punching device according to claim 1 in which there are three of said retainer plate shoulders.

10. A punching device according to claim 1 in which said retainer plate has three vertical clearance walls arranged as three sides of a square, two of said clearance walls extending to two of said shoulders on said retainer plate, and the third extending for the thickness of said plate. 

1. A punching device comprising: a. a frame having a lower arm on which a die is supported, and an upper arm having a vertical bore aligned therewith; b. a punch-guide and stripper sleeve slidably disposed in the bore in said upper arm, there being a recess facing said bore and defining a shoulder facing away from said die; c. a punch having a body slidably disposed in said sleeve; d. a stripping spring acting between said sleeve and said punch to urge the lower end of said punch into said sleeve; e. a lifting spring acting between said sleeve and said upper arm and urging said sleeve away from said die; and f. a retainer plate movably secured to the upper side of said upper arm, said plate having a plurality of peripheral portions for overhanging Said bore and projecting into said recess of said sleeve, said portions each having a shoulder (1) facing toward said die, (2) being located at differing distances from said die, and (3) being respectively engageable with said shoulder on said sleeve in response to horizontal repositioning of said plate.
 2. A punching device according to claim 1 in which each of said peripheral portions project beneath said lifting spring for engaging said shoulder on said stripper sleeve.
 3. A punching device according to claim 1 in which the upper surface of said retainer plate is coplanar with the upper surface of said upper arm.
 4. A punching device according to claim 1 including a shoulder screw securing said plate to said upper arm, said shoulder screw having a central non-threaded bearing portion having a close fit with said retainer plate to position it accurately.
 5. A punching device according to claim 1 in which said plate is circular at each said peripheral portion, said plate having a further peripheral portion movable to a substantially tangential relation to said bore where it has clearance with respect to said stripper sleeve.
 6. A punching device according to claim 1 which includes detent means acting between said upper arm and said retainer plate for accurately locating each of said peripheral portions of said retainer plate.
 7. A punching device according to claim 6 in which said retainer plate is rotatably mounted for movement about a vertical axis, said detent means including a plurality of detent elements disposed a uniform distance from said axis.
 8. A punching device according to claim 7 in which said detent elements are ball-receptive recesses on said retainer plate.
 9. A punching device according to claim 1 in which there are three of said retainer plate shoulders.
 10. A punching device according to claim 1 in which said retainer plate has three vertical clearance walls arranged as three sides of a square, two of said clearance walls extending to two of said shoulders on said retainer plate, and the third extending for the thickness of said plate. 